This invention relates to biotechnology and more particularly to the biological protection of plants against viral and fungal infections. The invention concerns a new protein which was isolated from the bacterium Bacillus thuringiensis and which can be used for the biological control of plant diseases and also as a source for making transgenic plants with multiple resistance to different plant viruses and phytopathogenic fungi.
Less than 12 years ago biologists created the first transgenic plants. Since then, researchers have applied genetic engineering to more than 50 plants species. The technique has helped investigators gain critical insight into fundamental processes that govern the development of plants, and the first such genetically modified plants have been commercially introduced. Although genetic engineering is more complex than traditional plant breeding practices, it is just as safe. In both methods, new DNA enters the plant""s genome and is stably maintained and ex-pressed.
About 4 years ago a US National Academy of Sciences report concluded that xe2x80x9ccrops modified by molecular and cellular methods should pose risks no different from those modified by classical genetic methods for similar traitsxe2x80x9d. At about the same time the White House stated that genetically engineered products should not be subject to additional federal regulations, because they do not pose any unreasonable risk.
One of the most promising traits gene transfer offers is resistance to diseases. Exciting results have been achieved in creating plants resistant to viruses, an important matter because currently no direct way to treat virus-infected plants exists. Most infections reduce crop yield, but occasionally some prove to be catastrophic. Good farming practices, such as rotating crops and removing weeds and using meristem culture, can contain viruses, but only partially. Insecticides are sometimes used to control the pests responsible for transmitting viruses but in very specific and limited cases.
Investigators of Monsanto and some other companies constructed a vector to introduce and express phytovirus genes in different plants. The experiments with plants so modified have shown that the expression of the virus genes confers resistance only to the same virus strains. It means that plants with such specific resistance may have limited practical application. Nevertheless, workers have now engineered effective tolerance to more than a dozen different plant viruses in a broad range of crop species /Baulcombe, 1994/. But in each of these cases the problem of limited resistance is always a concern with the practical application of these plants. One of the possible ways of solving this problem is to use genes of factors which induce multiple resistance of plants.
The object of the invention is a protein MF2 or a functional derivative thereof with a new structure that can induce resistance of plants to viral and fungal infections. The structure of the protein is depicted in SEQ. ID. No. 2.
The invention also concerns an isolated DNA sequence encoding the said protein, the DNA having the sequence depicted in SEQ. ID. No. 1, as such, or as a part of any DNA sequence, or a fragment thereof, or it is a DNA sequence which has degenerate codons with respect to the DNA sequence defined above.
The invention also concerns a method of isolating and purifying the protein MF2 from bacterial cells expressing the said protein.
A further object of the invention is the use of the protein, or of compositions containing the same, as a plant protectant, for inducing resistance of plants to viral and fungal phytopathogens.